Virtual function tables are used in many computer languages, including C++, C#, Java, and others to enable dynamic dispatch, runtime method binding, and other features. An entry in a virtual function table may contain a reference to a method. When a class is derived from another class, the derived class inherits the contents of a virtual function table and may replace one or more of the references in the derived class's virtual function table with references to new functions. This mechanism enables a child class to receive the methods of the parent, but may replace one or more of those methods with new methods, in addition to adding more methods.
The inheritance capabilities of classes within these computer languages are typically implemented by creating a new virtual function table for each class. In cases where many such classes are used, the virtual function tables may consume large amounts of memory, leading to slow startup time and large resource usage.